The present invention relates to an apparatus used in the manufacturing of electric lamps and, more particularly, to an exhaust apparatus suitable for exhausting the bulbs of fluorescent lamps.
In manufacturing ring-shaped fluorescent lamps, the straight or elongated bulb made of lead glass is softened by heating and then is shaped in a ring by the bending machine. The bulbs thus shaped are fed to the exhaust apparatus, where the bulb exhaust step is done. This bulb exhaust step includes a process of introducing materials such as mercury and argon in the bulbs through their exhaust tubes, tipping off and closing their exhaust tubes, as well as exhausting the bulbs through their exhaust tubes. After this exhaust step, aging and base-attaching processes are applied to the bulbs to make the ring-shaped fluorescent lamps complete.
In the above-described procedure, it is desired that the time necessary for processing one of the bulbs be shortened to enhance productivity.
The exhaust apparatus for ring-shaped fluorescent lamps disclosed by Japanese Patent Publication No. 51-392 is well-known and is used in the exhaust step to enhance productivity. In this well-known exhaust apparatus, bulbs are attached to the front ends of radially extending support arms and the exhaust step is effected as the support arms intermittently rotate. This well-known exhaust apparatus is intended to shorten the exhaust time per bulb in the exhaust step in such a way that two of the support arms are paired to exhaust two bulbs at the same time.
In this rotary exhaust apparatus, a center plate or valve is used to change the passages which are connected to the exhaust tubes when exhausting the bulbs and introducing the materials within. However, in order to exhaust two bulbs simultaneously the internal structure of the center valve must become more complicated. In addition, since two bulbs are synchronizingly and intermittently conveyed to exhaust two bulbs at the same time, the circumference or radius of the exhaust apparatus must be large, making the overall apparatus large-sized. The complexity of the structure of the center valve and the largeness of the overall exhaust apparatus become even more intensified as the number of bulbs which are to be exhausted simultaneously is increased. Further, since the rotary exhaust apparatus is a circle, the floor on which it is installed cannot be effectively used.